The existing LED driver of the LCD device using the light-emitting diode (LED) as a backlight is shown in FIG. 1. The backlight driver comprises a light bar, wherein said light bar is provided with multiple LED strings which are in parallel connection; each LED string comprises multiple LED lights which are in series connection; one end of each LED string is connected with the forward voltage Vin, and the other end of each LED string is respectively connected to a constant current controller. The LED driver can monitor the voltage of each LED string in real time, feed back the minimum voltage to the power input, so as to regulate the value of the forward voltage Vin to ensure that the forward voltage Vin can meet the requirement of brightness of the minimum-voltage LED string. This way the LED input voltage is optimized. Meanwhile, in order to ensure the consistency of the LED brightness, the same current and duty driver are used by the constant-current control circuit to control different LED strings, as shown in FIG. 2. This ensures that the effective value of the currents of all LED strings are equal, so as to ensure the consistency of the LED brightness. In the embodiment, because the voltages of different LED strings are different, the difference will be added to the constant-current control circuit, causing consumption. Thus, the temperature of the constant-current control circuit is increased, and the efficiency of the power supply is reduced.